Videos and images may contain smoothly changing areas such as blue-sky background and shadings on the wall. In these areas, the luminance is changing gradually, which should be perceived as smooth areas. However, as video and images are stored digitally and the bit depth is limited, stage-like false contour artifacts are perceived in these areas.
To eliminate such artifacts, a higher precision content of the smoothly changing area is needed. Once the higher precision content is obtained, the content can be displayed on a higher bit depth display such that the steps between two consecutive luminance levels are too small to be perceived.
Alternatively, half-toning technique can be used (e.g., super dithering) to quantize the higher precision content to the display bit depth and remove the perceptual artifacts due to the spatial averaging characteristics of human visual system.
In either case, obtaining a higher precision content for the smoothly changing area is an essential step to removing these perceptional artifacts.